Advance in cell biology and recombinant protein technologies has led to the development of protein therapeutics.
Yet, major hurdles still exist. Most proteins are susceptible to proteolytic degradation and therefore have a short circulating time. Other disadvantages include low water solubility and inducement of neutralizing antibodies.
Attachment of a polymer, e.g., polyethylene glycol (PEG), to a protein hinders access of proteolytic enzymes to the protein backbone, resulting in enhanced protein stability. In addition, it may also improve water solubility and minimize immuogenicity. There is a need for effective methods of attaching polymer to proteins.